package com.atguigu.pratice;

import java.util.Scanner;

public class TheRabbitNum {
    public static void main(String[] args) {
        Scanner scanner=new Scanner(System.in);
        int n=scanner.nextInt();
        int res=findRabittNum(n);
        System.out.println(res);
    }

    private static int findRabittNum(int x) {
        if(x==1||x==2){
            return 1;
        }else{
            return findRabittNum(x-1)+findRabittNum(x-2);
        }
    }
}
